CN111535939B - A fuel injection system suitable for regenerative cooling detonation combustion chamber - Google Patents

Abstract

The invention provides a fuel injection system suitable for a regenerative cooling detonation combustion chamber, which mainly comprises a fuel tank, a fuel booster pump, a primary heat exchanger of the detonation combustion chamber, a secondary heat exchanger of the detonation combustion chamber, a heat regenerator, a bypass regulating valve, a low-pressure ratio turbine, an excitation generator, a gas-liquid separation chamber and an atomizing nozzle. The system transfers high heat flow on the wall surface of a combustion chamber by utilizing the expansion and the work of high-temperature and high-pressure hydrocarbon fuel in a turbine coaxially arranged with an excitation generator in the regenerative cooling process, realizes the conversion of heat energy to electric energy and improves the regenerative cooling capacity; the micromolecule gaseous fuel and the macromolecule liquid fuel are separated after cracking according to the density difference of the low-temperature and low-pressure mixed fuel after expansion work, and the micromolecule gaseous fuel with excellent initiation performance is sprayed into the combustion chamber in a mode of atomizing the liquid fuel by cyclone, so that the problem of pressure pulsation of the traditional mixed fuel can be solved, and uniform atomization and mixing are realized.

Description

A fuel injection system suitable for regenerative cooling detonation combustion chamber

technical field

The invention relates to the field of detonation engines, in particular to a fuel injection system suitable for regeneration and cooling of detonation combustion chambers.

Background technique

The detonation propulsion engine is a new concept engine based on detonation combustion. The chemical reaction rate of detonation combustion is extremely fast. The detonation wave generated by its combustion is directly used in the combustion chamber to compress the gas, and the fresh reactant is converted into High temperature and high pressure combustion products, so knock combustion is similar to constant volume combustion. Therefore, the engine thermal cycle based on knocking combustion has higher thermal efficiency than the traditional slow combustion method. In addition, the structure of the detonation engine is relatively simple, eliminating the need for components such as compressors and turbines, and has a high thrust-to-weight ratio. Based on the above advantages, the research of detonation combustion propulsion engine has received extensive attention, and it is an aerospace power device with broad application prospects.

Using liquid fuel as aerospace power propellant has the advantages of high energy density, easy storage, good cooling performance and high safety. How to realize rapid ignition and detonation of liquid fuel in detonation propulsion power plant has always been an important research topic. For complex liquid hydrocarbon fuel, due to the existence of problems such as poor atomization, poor working stability and poor detonation performance, its DDT (Deflagration to Detonation Transition) time and ignition delay time are nearly an order of magnitude larger than gaseous fuel. In addition, when using liquid fuel, the flue gas temperature after detonation combustion exceeds 2000K, which exceeds the maximum temperature that the wall material can withstand, and when the tube wall temperature is greater than the self-ignition temperature of the fuel, the fuel injected into the detonation combustion chamber will Spontaneous combustion will occur, at which point knocking fails. Based on this problem, the regenerative cooling scheme of coating the cracking catalyst in the cooling ring cavity is widely used because it can cool the wall of the combustion chamber and obtain small-molecule gaseous fuel with excellent detonation performance. However, with the increase of the working frequency or the long-term operation, the amount of heat released by the detonation combustion increases sharply, and the high wall temperature of the combustion chamber will cause the fuel to coke and deposit, which will block the passages and pipelines. The regenerative cooling process cannot meet the cooling demand. In addition, in the traditional regenerative cooling scheme of the cracking catalyst coated in the cooling ring cavity, due to factors such as the coating area, only a small part of the hydrocarbon fuel can be fully contacted with the catalyst, and the thermal cracking efficiency is extremely low. It is easy to coke, and the types of hydrocarbon fuel components are very complex, and the physical and chemical properties of each component are very different. Under the same conditions, it is impossible to completely crack the liquid hydrocarbon fuel into small molecular gaseous fuel with excellent detonation performance, and finally high temperature gas/liquid The mixed fuel is injected into the combustion chamber, and the large density difference of the gas/liquid mixed fuel will lead to the pulsation of the injection pressure, the injection instability, the deterioration of the mixing and atomization, and the reduction of the detonation and combustion performance.

In view of the above problems, it is necessary to propose a new system based on the original regenerative cooling scheme to realize the transfer of high heat flow on the wall of the detonation combustion chamber during high frequency and long-term operation and to control the injection process of the mixed fuel after endothermic cracking, so as to solve the problem. At the same time, the problem of protection of hot end components is obtained, and uniform atomization and blending of fuel in the detonation combustion chamber is obtained.

SUMMARY OF THE INVENTION

technical problem to be solved

Combined with the existing research and design scheme of regenerative cooling detonation combustion chamber, the present invention proposes a fuel injection system suitable for regenerative cooling detonation combustion chamber, so as to solve the pressure pulsation problem of gas/liquid mixed fuel injection, and realize uniform atomization and mixing. At the same time, it can meet the cooling requirements of the detonation combustion chamber wall under high-frequency long-term working conditions.

The technical scheme of the present invention is:

The fuel injection system suitable for regenerative cooling of the detonation combustion chamber mainly includes a fuel tank, a fuel booster pump, a first-stage heat exchanger of the detonation combustion chamber, a second-stage heat exchanger of the detonation combustion chamber, a return Heater, bypass regulating valve, low pressure ratio turbine, excitation generator, gas-liquid separation chamber and atomizing nozzle.

The outlet of the fuel tank is communicated with the inlet of the fuel booster pump, the outlet of the fuel booster pump is communicated with the inlet of the first-stage heat exchanger of the detonation combustion chamber, and the outlet of the first-stage heat exchanger of the detonation combustion chamber is communicated with the inlet of the first-stage heat exchanger of the detonation combustion chamber. The mixed-state fuel inlet of the regenerator is communicated, the mixed-state fuel outlet of the regenerator is communicated with the low-pressure ratio turbine inlet, and the low-pressure ratio turbine outlet is communicated with the mixed-state fuel inlet of the gas-liquid separation chamber, and the gas-liquid separation The gaseous fuel outlet of the chamber is communicated with the gaseous fuel inlet of the regenerator, the liquid fuel outlet of the gas-liquid separation chamber is communicated with the inlet of the second-stage heat exchanger of the detonation combustion chamber, and the gaseous fuel outlet of the regenerator is communicated with the atomizing nozzle The inlet of the gas passage is connected, the outlet of the second-stage heat exchanger of the detonation combustion chamber is communicated with the inlet of the oil passage of the atomizing nozzle, and the bypass regulating valve is installed on the parallel passage of the gaseous fuel pipeline of the regenerator, so The low pressure ratio turbine is installed coaxially with the excitation generator.

The fuel booster pump is used for boosting the liquid hydrocarbon fuel at normal temperature and pressure, ensuring that the outlet back pressure of the first-stage heat exchanger of the knocking combustion chamber is not lower than the critical pressure of the hydrocarbon fuel used.

The first-stage heat exchanger of the detonation combustion chamber is installed on the outer wall of the DDT section where the heat flow of the detonation combustion chamber is large, so as to realize a large temperature increase in the flow process of the low-temperature and high-pressure hydrocarbon fuel, and the inner wall of the first-stage heat exchanger is installed. Coated with hydrocarbon fuel efficient cracking catalyst to realize partial cracking of hydrocarbon fuel into small molecule gaseous fuel with excellent detonation performance, and finally obtain low viscosity and fluidity at the outlet of the first-stage heat exchanger of the detonation combustion chamber The strong supercritical/gaseous mixed fuel avoids its excessive flow resistance in the mixed fuel flow chamber of the regenerator, and at the same time reduces the density difference of the mixed fuel and improves the flow stability.

The second-stage heat exchanger of the detonation combustion chamber is installed on the outer wall of the detonation propagation section where the heat flow of the detonation combustion chamber is small, so as to realize a small temperature increase of the macromolecular liquid fuel after being separated by gas and liquid, and avoid the atomization nozzle. The high inlet temperature of the oil circuit leads to an excessive decrease in the ignition induction period after mixing with the oxidant, and then spontaneous combustion occurs and the knocking fails.

The outlet of the first-stage heat exchanger of the detonation combustion chamber is adjacent to the outlet of the second-stage heat exchanger of the detonation combustion chamber along the axial direction of the combustion chamber wall, so as to avoid the excessive temperature gradient of the combustion chamber wall in the axial direction. lead to local stress concentration.

The regenerator structure is a simple helical structure with a gaseous fuel flow channel built into the mixed fuel flow cavity, ensuring a small flow resistance of the mixed fuel, reducing power consumption, and at the same time having a certain ability to stabilize the flow before the turbine, avoiding large The pressure fluctuations cause a sudden impact on the turbine blade surface.

The bypass regulating valve is installed on the parallel channel of the gaseous fuel pipeline of the regenerator, and can adjust the heat recovery flow of the gaseous fuel according to the heat released by the combustion chamber wall within a certain range, that is, when the heat flow of the combustion chamber wall is high, the heat recovery When the flow rate decreases, the fuel enthalpy value at the inlet of the turbine increases, and more heat energy is converted into electrical energy to realize the timely transfer of the wall heat flow; while when the wall heat flow of the combustion chamber is low, the regenerative heat flow increases, and the fuel enthalpy at the inlet of the gas path of the atomizing nozzle increases. When the value increases, the detonation performance of small molecular gaseous fuel is improved, and the decreasing trend of detonation performance caused by the low heat flow on the wall is alleviated.

The low-pressure ratio turbine is installed coaxially with the excitation generator, and the heat flow on the combustion chamber wall is transferred by the expansion of high-temperature and high-pressure hydrocarbon fuel in the turbine, so as to realize the conversion of thermal energy into electric energy, and improve the regenerative cooling capacity. Combustion provides an efficient means of generating electricity for the propulsion system of the power main body.

The gas-liquid separation chamber realizes the separation of the small molecular gaseous fuel and the macromolecular liquid fuel after the cracking according to the large density difference of the low-temperature and low-pressure mixed fuel after the expansion work, so as to avoid the density difference caused by the gas/liquid mixed fuel injection. pressure pulsation, uneven mixing and atomization, detonation and unstable combustion.

The atomizing nozzle adopts two inlets of oil circuit and gas circuit, and due to the different resistance of the pipeline, the pressure of the gas inlet is slightly higher than that of the oil inlet. The fuel is sprayed into the combustion chamber by means of swirling atomization of macromolecular liquid fuel to achieve uniform mixing and atomization.

beneficial effect

(1) The normal temperature and normal pressure hydrocarbon fuel passes through the fuel injection system, and is finally injected into the combustion chamber in the form of small molecular gaseous fuel with excellent detonation performance swirling and atomized macromolecular liquid fuel, which can avoid the injection of gas-liquid mixed fuel. Pressure pulsation, uneven mixing and atomization, poor detonation performance and combustion instability caused by density difference.

(2) In the fuel injection system, through the regenerative cooling process, the high-temperature and high-pressure hydrocarbon fuel obtained after the first-stage heat exchanger of the detonation combustion chamber absorbs heat is introduced into a turbine installed coaxially with the excitation generator to expand and do work. It transfers the high heat flow on the wall of the combustion chamber, realizes the conversion and utilization of energy, improves the regenerative cooling capacity, ensures the high-frequency continuous and reliable operation of the detonation combustion chamber, and provides an effective power generation method for the propulsion system based on detonation combustion as the main power.

Description of drawings

1 is a schematic diagram of a fuel injection system suitable for regenerative cooling of a detonating combustion chamber (thin dashed lines are gaseous fuel lines, thick dashed lines are supercritical/gaseous mixed fuel lines, and solid lines are liquid fuel lines).

In the figure, 1 is the fuel tank, 2 is the bypass regulating valve, 3 is the regenerator gaseous fuel flow pipeline, 4 is the regenerator, 5 is the regenerator mixed fuel flow chamber, 6 is the low pressure ratio turbine, 7 is the excitation generator, 8 is the gas-liquid separation chamber, 9 is the inlet of the second-stage heat exchanger of the detonation combustion chamber, 10 is the second-stage heat exchanger of the detonation combustion chamber, and 11 is the first-stage heat exchanger of the detonation combustion chamber Heater outlet, 12 is the outlet of the second-stage heat exchanger of the detonation combustion chamber, 13 is the wall surface of the detonation combustion chamber, 14 is the first-stage heat exchanger of the detonation combustion chamber, and 15 is the first-stage heat exchange of the detonation combustion chamber 16 is the spark plug, 17 is the atomizing nozzle, 18 is the oxidant inlet, and 19 is the fuel booster pump.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings.

The present invention is a fuel injection system suitable for regenerative cooling detonation combustion chamber, as shown in FIG. 1 , which includes: fuel tank 1, bypass regulating valve 2, regenerator gaseous fuel flow pipeline 3, regenerator 4. The regenerator mixed fuel flow chamber 5, the low pressure ratio turbine 6, the excitation generator 7, the gas-liquid separation chamber 8, the second-stage heat exchanger inlet of the detonation combustion chamber 9, the second-stage exchange of the detonation combustion chamber Heater 10, first-stage heat exchanger outlet 11 of detonation combustion chamber, second-stage heat exchanger outlet 12 of detonation combustion chamber, wall surface of detonation combustion chamber 13, first-stage heat exchanger 14 of detonation combustion chamber, detonation combustion chamber The first-stage heat exchanger inlet 15 , spark plug 16 , atomizing nozzle 17 , oxidant inlet 18 and fuel booster pump 19 in the shock combustion chamber.

The described fuel injection system suitable for regenerative cooling detonation combustion chamber is characterized in that: the first-stage heat exchanger 14 of the detonation combustion chamber is installed on the outer wall of the DDT section where the heat flow of the detonation combustion chamber wall 13 is large. , the second-stage heat exchanger 10 of the detonation combustion chamber is installed on the outer wall of the detonation propagation section where the heat flow is small on the wall surface 13 of the detonation combustion chamber, and the inner wall of the first-stage heat exchanger 14 of the detonation combustion chamber is coated with hydrocarbons Fuel efficient cracking catalyst, the outlet 11 of the first-stage heat exchanger of the detonation combustion chamber is axially adjacent to the outlet 12 of the second-stage heat exchanger of the detonation combustion chamber, the outlet of the fuel tank 1 and the inlet of the fuel booster pump 19 The outlet of the fuel booster pump 19 is communicated with the inlet 14 of the first-stage heat exchanger of the detonation combustion chamber, and the outlet 11 of the first-stage heat exchanger of the detonation combustion chamber is connected to the mixed fuel flow capacity of the regenerator. The inlet of the cavity 5 is communicated with the inlet of the cavity 5, the outlet of the regenerator mixed fuel flow chamber 5 is communicated with the inlet of the low pressure ratio turbine 6, and the outlet of the low pressure ratio turbine 6 is communicated with the mixed state fuel inlet of the gas-liquid separation chamber 8. The gaseous fuel outlet of the gas-liquid separation chamber 8 is communicated with the inlet of the gaseous fuel flow pipeline 3 of the regenerator, and the liquid fuel outlet of the gas-liquid separation chamber 8 is communicated with the second-stage heat exchanger inlet 9 of the detonation combustion chamber. The outlet of the gaseous fuel flow line 3 of the regenerator is communicated with the air inlet of the atomizing nozzle 17, and the outlet 12 of the second-stage heat exchanger of the detonation combustion chamber is communicated with the oil inlet of the atomizing nozzle 17. The bypass The regulating valve 2 is installed on the parallel passage of the regenerator gaseous fuel flow line 3 , and the low pressure ratio turbine 6 is installed coaxially with the excitation generator 7 .

work process

The described fuel injection system suitable for regenerative cooling detonation combustion chamber, when working, the normal temperature and normal pressure liquid hydrocarbon fuel in the fuel tank 1 is pressurized to supercritical pressure by the fuel booster pump 19, and then flows through the fuel tank 1. The first-stage heat exchanger 14 of the detonation combustor coated with a high-efficiency cracking catalyst is endothermic and cracked to form a high-temperature and high-pressure supercritical/gaseous mixed fuel, which then enters the regenerator mixed-state fuel flow volume 5, and is further expanded through the low pressure ratio turbine 6 The work drives the excitation generator 7 installed coaxially with it, realizes the transfer of heat flow on the wall of the combustion chamber and completes the conversion to electrical energy; the low-temperature and low-pressure gas/liquid mixed fuel formed after expansion enters the gas-liquid separation chamber 8, and the low-temperature and low-pressure mixed state fuel Due to the large density difference, the separation of the cracked small molecule gaseous fuel and the macromolecular liquid fuel is realized; the gaseous fuel in the upper part of the gas-liquid separation chamber 8 flows through the regenerator gaseous fuel flow pipeline 3 to absorb heat and heat up, and the other way flows through Bypass regulating valve 2, the two are mixed and flow into the gas path inlet of atomizing nozzle 17, the lower liquid fuel absorbs heat and heats up through the second-stage heat exchanger 10 of the detonation combustion chamber to form high temperature liquid fuel and then enters the oil path inlet of atomizing nozzle 17 ; Due to the small flow resistance of the gaseous fuel pipeline, the fuel supply of the system is finally injected into the combustion chamber by swirling and atomizing the liquid fuel of the small molecular gaseous fuel with a slightly higher pressure and excellent detonation performance. Within a certain range, if the heat flow on the wall 13 of the knocking combustion chamber is relatively high, the opening of the bypass control valve 2 increases, the gaseous fuel recuperation flow decreases, the low-pressure ratio turbine 6 inlet fuel enthalpy increases, and more heat energy is converted into When the heat flow on the wall 13 of the detonation combustion chamber is low, the opening of the bypass control valve 2 decreases, the gaseous fuel recuperation flow increases, and the fuel enthalpy value at the gas path inlet of the atomizing nozzle 17 increases. , to improve the detonation performance of small molecular gaseous fuels, and to alleviate the decreasing trend of detonation performance caused by the reduction of wall heat flow.

The specific embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings and specific working processes, but the present invention is not limited to the above-mentioned embodiments. should be within the protection scope of the present invention.

Claims (6)

1. a fuel injection system suitable for regenerative cooling detonation combustion chamber, is characterized in that: comprise fuel tank, fuel booster pump, detonation combustion chamber first-stage heat exchanger, detonation combustion chamber second-stage heat exchange radiator, regenerator, bypass regulating valve, low pressure ratio turbine, excitation generator, gas-liquid separation chamber and atomizing nozzle; the fuel tank outlet is communicated with the fuel booster pump inlet, and the fuel booster pump outlet is The inlet of the first-stage heat exchanger of the detonation combustion chamber is communicated, and the outlet of the first-stage heat exchanger of the detonation combustion chamber is communicated with the inlet of the mixed-state fuel of the regenerator, and the mixed-state fuel outlet of the regenerator is proportional to the low pressure ratio The turbine inlet is communicated, the low pressure ratio turbine outlet is communicated with the mixed fuel inlet of the gas-liquid separation chamber, the gaseous fuel outlet of the gas-liquid separation chamber is communicated with the gaseous fuel inlet of the regenerator, and the liquid fuel of the gas-liquid separation chamber is communicated The outlet is communicated with the inlet of the second-stage heat exchanger of the detonation combustion chamber, the gaseous fuel outlet of the regenerator is communicated with the gas passage inlet of the atomizing nozzle, and the outlet of the second-stage heat exchanger of the detonation combustion chamber is communicated with the atomization nozzle. The inlet of the nozzle oil passage is connected, the bypass regulating valve is installed on the parallel passage of the gaseous fuel pipeline of the regenerator, and the low pressure ratio turbine is installed coaxially with the excitation generator. 2. A fuel injection system suitable for regenerative cooling of a detonation combustion chamber according to claim 1, wherein the first-stage heat exchanger of the detonation combustion chamber is installed in a place where the heat flow of the detonation combustion chamber is large. The outer wall of the DDT section is coated with a hydrocarbon fuel cracking catalyst; the second-stage heat exchanger of the detonation combustion chamber is installed on the outer wall of the detonation propagation section where the heat flow of the detonation combustion chamber is small, and the outlet is liquid fuel; The outlet of the first-stage heat exchanger of the detonation combustion chamber is axially adjacent to the outlet of the second-stage heat exchanger of the detonation combustion chamber, so as to avoid an excessive axial temperature gradient on the wall of the detonation combustion chamber. 3. A fuel injection system suitable for regenerative cooling detonation combustion chamber according to claim 1, characterized in that: the bypass regulating valve is installed on the parallel passage of the gaseous fuel pipeline of the regenerator, and at a certain Within the range, the gaseous fuel recuperation flow is adjusted according to the heat flow of the combustion chamber wall, so that the wall of the combustion chamber can be cooled in time when the heat flow is high and the fuel can be detonated quickly when the heat flow is low. 4 . The fuel injection system according to claim 1 , wherein the regenerator structure is a gaseous fuel flow channel with a simple helical structure built into the mixed fuel flow volume. 5 . The cavity ensures a small flow resistance of the mixed fuel, and at the same time has a certain ability to stabilize the flow before the turbine, reducing the instantaneous pressure impact on the turbine blade surface. 5. A fuel injection system suitable for regenerative cooling of a detonation combustion chamber according to claim 1, wherein the system injects the high temperature and high pressure obtained after the first-stage heat exchanger of the detonation combustion chamber absorbs heat The hydrocarbon fuel is introduced into the turbine installed coaxially with the excitation generator to expand and do work to transfer the high heat flow on the combustion chamber wall, realize the conversion of thermal energy into electrical energy, transfer the wall heat flow in time, and improve the regenerative cooling capacity. 6 . A fuel injection system suitable for regenerative cooling detonation combustion chamber according to claim 1 , wherein the system utilizes the density difference of the low-temperature and low-pressure mixed fuel after expansion work to realize the cracked small molecules. 7 . The gaseous fuel is separated from the macromolecular liquid fuel, and injected into the detonation combustion chamber by swirling and atomized liquid fuel of small molecular gaseous fuel with excellent detonation performance, which solves the problem of injection pressure pulsation and realizes uniform mixing and atomization.

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